The present invention is concerned with a circuit for performing demodulation of phase or amplitude modulated time-varying signals. Although various types of demodulators are known in the art, none are capable of operating directly on signals having frequencies ranging from the audio into the gigaHertz (GHz) range. Those UHF and SHF demodulators which do exist are fairly complex, and there are limits in the type of applications in which such devices can be used.
Morevover, the present invention is preferably implemented as a semiconductor integrated circuit using charge coupled device (CCD) technology. More particularly, the device uses a known type of CCD input circuit known as the Tompsett or "fill and spill" input, described in U.S. Pat. No. 3,881,117.
Although various applications of CCD circuits to high frequency signal processing are known (e.g., U.S. Pat. Nos. 4,152,606 and 4,159,430), it was not known in the prior art to directly apply the "fill and spill"0 input circuit to RF signals. Moreover, there was no teaching to such prior art about the desirability of using CCD technology in radio frequency circuit applications.